The present invention relates generally to combine harvesters, and more specifically, an apparatus and method for improving the cleaning process in a combine harvester.
Combine harvesters having axial flow and separation units are known in the art. The separation unit separates grain kernels from harvested materials. Working elements of a separation rotor contact and beat the harvested material, wherein the beating is similar to a threshing action. Members, such as special beaters and rasp bars, can be operatively arranged on the rotor element and on internal surfaces of the rotor housing, which produce a special threshing effect, but they are not necessary for the rotary threshing and separation unit. There may be additional threshing elements arranged outside of the rotary threshing and separation unit. The separation units may be arranged in a longitudinal direction or transverse to the travelling direction of the combine harvester. There may be one or two rotor housings operatively arranged on the same or on different levels or arranged horizontally or inclined on an angle. There may be one or more rotors operatively arranged in a rotor housing. If two or more rotors are used, they may rotate in the same or opposite direction with respect to each other.
The separation unit has a high separation capacity due to the high centrifugal forces being applied to the harvested material in the rotor housing resulting not only in grain kernels, but also the chaff and broken straw, being separated from the harvested materials. This mixture of grain kernels, chaff and broken straw needs to be separated to achieve a clean sample of grain kernels, which is collected in the grain bin. This cleaning process is usually achieved by a special cleaning apparatus, such as a conventional sieve, through which air is blown from below. As such, the lighter fractions like the chaff and the broken straw are carried away by the blowing air and blown out of the combine harvester and the heavier grain kernels fall through the sieve openings. There are various cleaning apparatuses known to those skilled in the art. A common disadvantage with these cleaning apparatuses is that the capacity may not be as high as the separation capacity of the separation unit, thereby limiting the throughput capacity of the combine harvester.
Attempts have been made to increase the cleaning capacity of a combine harvester. U.S. Pat. No. 4,869,272 describes a cross-flow fan located adjacent to an inlet end of a threshing cage to direct air past the threshing cage to provide a more efficient separation of the grain from the chaff or the broken straw. However, this device utilizes air from an upper sieve area of the cleaning apparatus, creating a very strong air flow through an initial portion of the sieves, and the grain kernels passing therein tend to be blown upwards precluding the grain kernels from passing through the openings in the sieve of the cleaning apparatus. Additionally, the air passing the sieve openings is reduced because the air from the cleaning apparatus is blown upwards into the direction of a cross-flow fan; hence, the cleaning action in this area is also reduced. Because there are two cross-flow fans arranged beside a single rotor housing, the air flow along the lateral direction over the sieves is disturbed. As a result, the cleaning performance of the cleaning apparatus is adversely affected by the cross-flow fans.
German Patent No. DE 196 24 733 attempts to increase the cleaning performance of a combine harvester by an additional air flow stream generating mechanism. An air flow stream is directed through a space between conventional straw walkers, which is used for separation of grain kernels from harvested material, and as a grain collecting element arranged underneath the straw walkers to reduce the adverse effects on the cleaning process. To direct away the chaff and the broken straw from grain kernels accumulating on the grain collecting element, high air flow speeds are necessary. Due to this increase in speed, there is a higher probability that the grain kernels, which have been separated from the harvested material by the straw walkers, will not fall onto the grain collecting element and will be sucked into the blower unit and blown out of the combine harvester, resulting in crop loss. Another disadvantage is that due to the large number of openings in the conventional straw walkers, the air flow stream generated by the blower unit is sucked into the space underneath the straw walkers through the openings from the space above the straw walkers, and by this air flow stream, additional chaff and broken straw is sucked through the straw walker openings which is not desirable.
The present invention is directed to overcoming one or more of the problems set forth above.
An aspect of the present invention is to provide a sucking blower unit for a combine harvester to improve and increase the cleaning capacity.
In another aspect of the present invention there is provided a method for improving and increasing the cleaning capacity of a combine harvester.
In another aspect of the present invention there is provided an apparatus and method for producing an air stream to improve and increase the cleaning process.
Another aspect of the present invention there is provided an apparatus for improving and increasing the cleaning capacity that can be retrofitted for existing combine harvesters.
In accordance with the present invention there is provided a combine harvester for harvesting crop and separating grain from chaff and broken straw, including a separation unit for separating the grain from the harvested crop; at least one rotor housing with a sieve mechanism, wherein the sieve mechanism has a plurality of sieve openings therein; a rotor operatively and rotatably mounted in the at least one rotor housing; a grain collecting element operatively mounted adjacent to and for receiving the grain from the sieve mechanism; a cleaning apparatus for receiving grain collected from the grain collecting element; a sucking blower unit for sucking an air flow stream towards the sucking blower unit, wherein the air flow stream is drawn upwardly through a conduit operatively connected thereto; and wherein the conduit directs the air flow stream from a space between the at least one rotor housing of the separation unit and the grain collecting element in a semi-circular movement towards the sucking blower unit.
The above aspects are merely illustrative and should not be construed as all-inclusive. The aspects should not be construed as limiting the scope of the invention. The aspects and advantages of the present invention will become apparent, as it becomes better understood from the following detailed description when taken in conjunction with the accompanying drawings.